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Caesar cipher

Caesar cipher, is one of the simplest and most widely known encryption techniques. The transformation can be represented by aligning two alphabets, the cipher alphabet is the plain alphabet rotated left or right by some number of positions.

When encrypting, a person looks up each letter of the message in the 'plain' line and writes down the corresponding letter in the 'cipher' line. Deciphering is done in reverse.
The encryption can also be represented using modular arithmetic by first transforming the letters into numbers, according to the scheme, A = 0, B = 1,..., Z = 25. Encryption of a letter x by a shift n can be described mathematically as

Plaintext: rjenks
cipher variations:
skfolt tlgpmu umhqnv vnirow wojspx
xpktqy yqlurz zrmvsa asnwtb btoxuc
cupyvd dvqzwe ewraxf fxsbyg gytczh
hzudai iavebj jbwfck kcxgdl ldyhem
mezifn nfajgo ogbkhp phcliq qidmjr

Decryption is performed similarly,

(There are different definitions for the modulo operation. In the above, the result is in the range 0...25. I.e., if x+n or x-n are not in the range 0...25, we have to subtract or add 26.)
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Atbash Cipher

Atbash is an ancient encryption system created in the Middle East. It was originally used in the Hebrew language.
The Atbash cipher is a simple substitution cipher that relies on transposing all the letters in the alphabet such that the resulting alphabet is backwards.
The first letter is replaced with the last letter, the second with the second-last, and so on.
An example plaintext to ciphertext using Atbash:
Plain: rjenks
Cipher: iqvmph

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Baconian Cipher

To encode a message, each letter of the plaintext is replaced by a group of five of the letters 'A' or 'B'. This replacement is done according to the alphabet of the Baconian cipher, shown below.
a   AAAAA   g    AABBA     m    ABABB   s    BAAAB     y    BABBA
b   AAAAB   h    AABBB     n    ABBAA   t    BAABA     z    BABBB
c   AAABA   i    ABAAA     o    ABBAB   u    BAABB 
d   AAABB   j    BBBAA     p    ABBBA   v    BBBAB
e   AABAA   k    ABAAB     q    ABBBB   w    BABAA
f   AABAB   l    ABABA     r    BAAAA   x    BABAB

Plain: rjenks

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Affine Cipher
In the affine cipher the letters of an alphabet of size m are first mapped to the integers in the range 0..m - 1. It then uses modular arithmetic to transform the integer that each plaintext letter corresponds to into another integer that correspond to a ciphertext letter. The encryption function for a single letter is

where modulus m is the size of the alphabet and a and b are the key of the cipher. The value a must be chosen such that a and m are coprime.
Considering the specific case of encrypting messages in English (i.e. m = 26), there are a total of 286 non-trivial affine ciphers, not counting the 26 trivial Caesar ciphers. This number comes from the fact there are 12 numbers that are coprime with 26 that are less than 26 (these are the possible values of a). Each value of a can have 26 different addition shifts (the b value) ; therefore, there are 12*26 or 312 possible keys.
Plaintext: rjenks
cipher variations:

The decryption function is

where a - 1 is the modular multiplicative inverse of a modulo m. I.e., it satisfies the equation

The multiplicative inverse of a only exists if a and m are coprime. Hence without the restriction on a decryption might not be possible. It can be shown as follows that decryption function is the inverse of the encryption function,

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ROT13 Cipher
Applying ROT13 to a piece of text merely requires examining its alphabetic characters and replacing each one by the letter 13 places further along in the alphabet, wrapping back to the beginning if necessary. A becomes N, B becomes O, and so on up to M, which becomes Z, then the sequence continues at the beginning of the alphabet: N becomes A, O becomes B, and so on to Z, which becomes M. Only those letters which occur in the English alphabet are affected; numbers, symbols, whitespace, and all other characters are left unchanged. Because there are 26 letters in the English alphabet and 26 = 2 * 13, the ROT13 function is its own inverse:

ROT13(ROT13(x)) = x for any basic Latin-alphabet text x

An example plaintext to ciphertext using ROT13:

Plain: rjenks
Cipher: ewraxf

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Polybius Square

A Polybius Square is a table that allows someone to translate letters into numbers. To give a small level of encryption, this table can be randomized and shared with the recipient. In order to fit the 26 letters of the alphabet into the 25 spots created by the table, the letters i and j are usually combined.
1 2 3 4 5
1 A B C D E
2 F G H I/J K
3 L M N O P
4 Q R S T U
5 V W X Y Z

Basic Form:
Plain: rjenks
Cipher: 244251335234

Extended Methods:
Method #1

Plaintext: rjenks
method variations:

Method #2
Bifid cipher
The message is converted to its coordinates in the usual manner, but they are written vertically beneath:
r j e n k s 
2 4 5 3 5 3 
4 2 1 3 2 4 
They are then read out in rows:
Then divided up into pairs again, and the pairs turned back into letters using the square:
Plain: rjenks
Cipher: rppilr

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Method #3

Plaintext: rjenks
method variations:
twlxmi wlxmit lxmitw
xmitwl mitwlx itwlxm

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Permutation Cipher
In classical cryptography, a permutation cipher is a transposition cipher in which the key is a permutation. To apply a cipher, a random permutation of size E is generated (the larger the value of E the more secure the cipher). The plaintext is then broken into segments of size E and the letters within that segment are permuted according to this key.
In theory, any transposition cipher can be viewed as a permutation cipher where E is equal to the length of the plaintext; this is too cumbersome a generalisation to use in actual practice, however.
The idea behind a permutation cipher is to keep the plaintext characters unchanged, butalter their positions by rearrangement using a permutation
This cipher is defined as:
Let m be a positive integer, and K consist of all permutations of {1,...,m}
For a key (permutation) , define:
The encryption function
The decryption function
A small example, assuming m = 6, and the key is the permutation :

The first row is the value of i, and the second row is the corresponding value of (i)
The inverse permutation, is constructed by interchanging the two rows, andrearranging the columns so that the first row is in increasing order, Therefore, is:

Total variation formula:

e = 2,718281828 , n - plaintext length

Plaintext: rjenks

all 720 cipher variations:
rjenks rjensk rjekns rjeksn rjeskn rjesnk rjneks rjnesk rjnkes rjnkse rjnske
rjnsek rjknes rjknse rjkens rjkesn rjksen rjksne rjsnke rjsnek rjskne rjsken
rjsekn rjsenk rejnks rejnsk rejkns rejksn rejskn rejsnk renjks renjsk renkjs
renksj renskj rensjk reknjs reknsj rekjns rekjsn reksjn reksnj resnkj resnjk
resknj reskjn resjkn resjnk rnejks rnejsk rnekjs rneksj rneskj rnesjk rnjeks
rnjesk rnjkes rnjkse rnjske rnjsek rnkjes rnkjse rnkejs rnkesj rnksej rnksje
rnsjke rnsjek rnskje rnskej rnsekj rnsejk rkenjs rkensj rkejns rkejsn rkesjn
rkesnj rknejs rknesj rknjes rknjse rknsje rknsej rkjnes rkjnse rkjens rkjesn
rkjsen rkjsne rksnje rksnej rksjne rksjen rksejn rksenj rsenkj rsenjk rseknj
rsekjn rsejkn rsejnk rsnekj rsnejk rsnkej rsnkje rsnjke rsnjek rsknej rsknje
rskenj rskejn rskjen rskjne rsjnke rsjnek rsjkne rsjken rsjekn rsjenk jrenks
jrensk jrekns jreksn jreskn jresnk jrneks jrnesk jrnkes jrnkse jrnske jrnsek
jrknes jrknse jrkens jrkesn jrksen jrksne jrsnke jrsnek jrskne jrsken jrsekn
jrsenk jernks jernsk jerkns jerksn jerskn jersnk jenrks jenrsk jenkrs jenksr
jenskr jensrk jeknrs jeknsr jekrns jekrsn jeksrn jeksnr jesnkr jesnrk jesknr
jeskrn jesrkn jesrnk jnerks jnersk jnekrs jneksr jneskr jnesrk jnreks jnresk
jnrkes jnrkse jnrske jnrsek jnkres jnkrse jnkers jnkesr jnkser jnksre jnsrke
jnsrek jnskre jnsker jnsekr jnserk jkenrs jkensr jkerns jkersn jkesrn jkesnr
jkners jknesr jknres jknrse jknsre jknser jkrnes jkrnse jkrens jkresn jkrsen
jkrsne jksnre jksner jksrne jksren jksern jksenr jsenkr jsenrk jseknr jsekrn
jserkn jsernk jsnekr jsnerk jsnker jsnkre jsnrke jsnrek jskner jsknre jskenr
jskern jskren jskrne jsrnke jsrnek jsrkne jsrken jsrekn jsrenk ejrnks ejrnsk
ejrkns ejrksn ejrskn ejrsnk ejnrks ejnrsk ejnkrs ejnksr ejnskr ejnsrk ejknrs
ejknsr ejkrns ejkrsn ejksrn ejksnr ejsnkr ejsnrk ejsknr ejskrn ejsrkn ejsrnk
erjnks erjnsk erjkns erjksn erjskn erjsnk ernjks ernjsk ernkjs ernksj ernskj
ernsjk erknjs erknsj erkjns erkjsn erksjn erksnj ersnkj ersnjk ersknj erskjn
ersjkn ersjnk enrjks enrjsk enrkjs enrksj enrskj enrsjk enjrks enjrsk enjkrs
enjksr enjskr enjsrk enkjrs enkjsr enkrjs enkrsj enksrj enksjr ensjkr ensjrk
enskjr enskrj ensrkj ensrjk ekrnjs ekrnsj ekrjns ekrjsn ekrsjn ekrsnj eknrjs
eknrsj eknjrs eknjsr eknsjr eknsrj ekjnrs ekjnsr ekjrns ekjrsn ekjsrn ekjsnr
eksnjr eksnrj eksjnr eksjrn eksrjn eksrnj esrnkj esrnjk esrknj esrkjn esrjkn
esrjnk esnrkj esnrjk esnkrj esnkjr esnjkr esnjrk esknrj esknjr eskrnj eskrjn
eskjrn eskjnr esjnkr esjnrk esjknr esjkrn esjrkn esjrnk njerks njersk njekrs
njeksr njeskr njesrk njreks njresk njrkes njrkse njrske njrsek njkres njkrse
njkers njkesr njkser njksre njsrke njsrek njskre njsker njsekr njserk nejrks
nejrsk nejkrs nejksr nejskr nejsrk nerjks nerjsk nerkjs nerksj nerskj nersjk
nekrjs nekrsj nekjrs nekjsr neksjr neksrj nesrkj nesrjk neskrj neskjr nesjkr
nesjrk nrejks nrejsk nrekjs nreksj nreskj nresjk nrjeks nrjesk nrjkes nrjkse
nrjske nrjsek nrkjes nrkjse nrkejs nrkesj nrksej nrksje nrsjke nrsjek nrskje
nrskej nrsekj nrsejk nkerjs nkersj nkejrs nkejsr nkesjr nkesrj nkrejs nkresj
nkrjes nkrjse nkrsje nkrsej nkjres nkjrse nkjers nkjesr nkjser nkjsre nksrje
nksrej nksjre nksjer nksejr nkserj nserkj nserjk nsekrj nsekjr nsejkr nsejrk
nsrekj nsrejk nsrkej nsrkje nsrjke nsrjek nskrej nskrje nskerj nskejr nskjer
nskjre nsjrke nsjrek nsjkre nsjker nsjekr nsjerk kjenrs kjensr kjerns kjersn
kjesrn kjesnr kjners kjnesr kjnres kjnrse kjnsre kjnser kjrnes kjrnse kjrens
kjresn kjrsen kjrsne kjsnre kjsner kjsrne kjsren kjsern kjsenr kejnrs kejnsr
kejrns kejrsn kejsrn kejsnr kenjrs kenjsr kenrjs kenrsj kensrj kensjr kernjs
kernsj kerjns kerjsn kersjn kersnj kesnrj kesnjr kesrnj kesrjn kesjrn kesjnr
knejrs knejsr knerjs knersj knesrj knesjr knjers knjesr knjres knjrse knjsre
knjser knrjes knrjse knrejs knresj knrsej knrsje knsjre knsjer knsrje knsrej
knserj knsejr krenjs krensj krejns krejsn kresjn kresnj krnejs krnesj krnjes
krnjse krnsje krnsej krjnes krjnse krjens krjesn krjsen krjsne krsnje krsnej
krsjne krsjen krsejn krsenj ksenrj ksenjr ksernj kserjn ksejrn ksejnr ksnerj
ksnejr ksnrej ksnrje ksnjre ksnjer ksrnej ksrnje ksrenj ksrejn ksrjen ksrjne
ksjnre ksjner ksjrne ksjren ksjern ksjenr sjenkr sjenrk sjeknr sjekrn sjerkn
sjernk sjnekr sjnerk sjnker sjnkre sjnrke sjnrek sjkner sjknre sjkenr sjkern
sjkren sjkrne sjrnke sjrnek sjrkne sjrken sjrekn sjrenk sejnkr sejnrk sejknr
sejkrn sejrkn sejrnk senjkr senjrk senkjr senkrj senrkj senrjk seknjr seknrj
sekjnr sekjrn sekrjn sekrnj sernkj sernjk serknj serkjn serjkn serjnk snejkr
snejrk snekjr snekrj snerkj snerjk snjekr snjerk snjker snjkre snjrke snjrek
snkjer snkjre snkejr snkerj snkrej snkrje snrjke snrjek snrkje snrkej snrekj
snrejk skenjr skenrj skejnr skejrn skerjn skernj sknejr sknerj sknjer sknjre
sknrje sknrej skjner skjnre skjenr skjern skjren skjrne skrnje skrnej skrjne
skrjen skrejn skrenj srenkj srenjk sreknj srekjn srejkn srejnk srnekj srnejk
srnkej srnkje srnjke srnjek srknej srknje srkenj srkejn srkjen srkjne srjnke
srjnek srjkne srjken srjekn srjenk

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